unsigned int
go_field_alignment (tree t)
{
unsigned int v;
v = TYPE_ALIGN (t);
#ifdef BIGGEST_FIELD_ALIGNMENT
if (v > BIGGEST_FIELD_ALIGNMENT)
v = BIGGEST_FIELD_ALIGNMENT;
#endif
#ifdef ADJUST_FIELD_ALIGN
{
tree field ATTRIBUTE_UNUSED;
field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL, t);
v = ADJUST_FIELD_ALIGN (field, v);
}
#endif
return v / BITS_PER_UNIT;
}
BOOL
objc_layout_structure_next_member (struct objc_struct_layout *layout)
{
register int desired_align = 0;
/* The following are used only if the field is a bitfield */
register const char *bfld_type = 0;
register int bfld_type_align = 0, bfld_field_size = 0;
/* The current type without the type qualifiers */
const char *type;
BOOL unionp = layout->original_type[-1] == _C_UNION_B;
/* Add the size of the previous field to the size of the record. */
if (layout->prev_type)
{
type = objc_skip_type_qualifiers (layout->prev_type);
if (unionp)
layout->record_size = MAX (layout->record_size,
objc_sizeof_type (type) * BITS_PER_UNIT);
else if (*type != _C_BFLD)
layout->record_size += objc_sizeof_type (type) * BITS_PER_UNIT;
else {
/* Get the bitfield's type */
for (bfld_type = type + 1;
isdigit ((unsigned char)*bfld_type);
bfld_type++)
/* do nothing */;
bfld_type_align = objc_alignof_type (bfld_type) * BITS_PER_UNIT;
bfld_field_size = atoi (objc_skip_typespec (bfld_type));
layout->record_size += bfld_field_size;
}
}
if ((unionp && *layout->type == _C_UNION_E)
|| (!unionp && *layout->type == _C_STRUCT_E))
return NO;
/* Skip the variable name if any */
layout->type = objc_skip_variable_name (layout->type);
type = objc_skip_type_qualifiers (layout->type);
if (*type != _C_BFLD)
desired_align = objc_alignof_type (type) * BITS_PER_UNIT;
else
{
desired_align = 1;
/* Skip the bitfield's offset */
for (bfld_type = type + 1;
isdigit ((unsigned char) *bfld_type);
bfld_type++)
/* do nothing */;
bfld_type_align = objc_alignof_type (bfld_type) * BITS_PER_UNIT;
bfld_field_size = atoi (objc_skip_typespec (bfld_type));
}
/* The following won't work for vectors. */
#ifdef BIGGEST_FIELD_ALIGNMENT
desired_align = MIN (desired_align, BIGGEST_FIELD_ALIGNMENT);
#endif
#ifdef ADJUST_FIELD_ALIGN
desired_align = ADJUST_FIELD_ALIGN (type, desired_align);
#endif
/* Record must have at least as much alignment as any field.
Otherwise, the alignment of the field within the record
is meaningless. */
#ifndef HAVE_BITFIELD_TYPE_MATTERS
layout->record_align = MAX (layout->record_align, desired_align);
#else /* PCC_BITFIELD_TYPE_MATTERS */
if (*type == _C_BFLD)
{
/* For these machines, a zero-length field does not
affect the alignment of the structure as a whole.
It does, however, affect the alignment of the next field
within the structure. */
if (bfld_field_size)
layout->record_align = MAX (layout->record_align, desired_align);
else
desired_align = objc_alignof_type (bfld_type) * BITS_PER_UNIT;
/* A named bit field of declared type `int'
forces the entire structure to have `int' alignment.
Q1: How is encoded this thing and how to check for it?
Q2: How to determine maximum_field_alignment at runtime? */
/* if (DECL_NAME (field) != 0) */
{
int type_align = bfld_type_align;
#if 0
if (maximum_field_alignment != 0)
type_align = MIN (type_align, maximum_field_alignment);
else if (DECL_PACKED (field))
type_align = MIN (type_align, BITS_PER_UNIT);
#endif
layout->record_align = MAX (layout->record_align, type_align);
}
}
else
layout->record_align = MAX (layout->record_align, desired_align);
#endif /* PCC_BITFIELD_TYPE_MATTERS */
/* Does this field automatically have alignment it needs
by virtue of the fields that precede it and the record's
own alignment? */
if (*type == _C_BFLD)
layout->record_size = atoi (type + 1);
else if (layout->record_size % desired_align != 0)
{
/* No, we need to skip space before this field.
Bump the cumulative size to multiple of field alignment. */
layout->record_size = ROUND (layout->record_size, desired_align);
}
/* Jump to the next field in record. */
layout->prev_type = layout->type;
layout->type = objc_skip_typespec (layout->type); /* skip component */
return YES;
}
